to determine where to place PHIs by iteratively comparing reaching definitions
at each block. That was just plain wrong. This version now computes the
dominator tree within the subset of the CFG where PHIs may need to be placed,
and then places the PHIs in the iterated dominance frontier of each definition.
The rest of the patch is mostly the same, with a few more performance
improvements added in.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@101612 91177308-0d34-0410-b5e6-96231b3b80d8
(what was I thinking?) and there's also a problem with LCSSA. I'll try again
later with fixes.
--- Reverse-merging r100263 into '.':
U lib/Transforms/Utils/SSAUpdater.cpp
--- Reverse-merging r100177 into '.':
G lib/Transforms/Utils/SSAUpdater.cpp
--- Reverse-merging r100148 into '.':
G lib/Transforms/Utils/SSAUpdater.cpp
--- Reverse-merging r100147 into '.':
U include/llvm/Transforms/Utils/SSAUpdater.h
G lib/Transforms/Utils/SSAUpdater.cpp
--- Reverse-merging r100131 into '.':
G include/llvm/Transforms/Utils/SSAUpdater.h
G lib/Transforms/Utils/SSAUpdater.cpp
--- Reverse-merging r100130 into '.':
G lib/Transforms/Utils/SSAUpdater.cpp
--- Reverse-merging r100126 into '.':
G include/llvm/Transforms/Utils/SSAUpdater.h
G lib/Transforms/Utils/SSAUpdater.cpp
--- Reverse-merging r100050 into '.':
D test/Transforms/GVN/2010-03-31-RedundantPHIs.ll
--- Reverse-merging r100047 into '.':
G include/llvm/Transforms/Utils/SSAUpdater.h
G lib/Transforms/Utils/SSAUpdater.cpp
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@100264 91177308-0d34-0410-b5e6-96231b3b80d8
unconditionally. Besides checking the offset, also check that the underlying
object is aligned as much as the load itself.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@94875 91177308-0d34-0410-b5e6-96231b3b80d8
This was already being done in SSAUpdater::GetValueAtEndOfBlock so I've
just changed SSAUpdater to check for existing PHIs in both places.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@94690 91177308-0d34-0410-b5e6-96231b3b80d8
cache a pointer as being unavailable due to phi trans in the
wrong place. This would cause later queries to fail even when
they didn't involve phi trans.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91787 91177308-0d34-0410-b5e6-96231b3b80d8
value size. This only manifested when memdep inprecisely returns clobber,
which is do to a caching issue in the PR5744 testcase. We can 'efficiently
emulate' this by using '-no-aa'
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91004 91177308-0d34-0410-b5e6-96231b3b80d8
clobbers to forward pieces of large stores to small loads, we need to consider
the properly phi translated pointer in the store block.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@90978 91177308-0d34-0410-b5e6-96231b3b80d8
add, there is no need to scan the world to find the same add again.
This invalidates the previous testcase, which wasn't wonderful anyway,
because it needed a run of instcombine to permute the use-lists in
just the right way to before GVN was run (so it was really fragile).
Not a big loss.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@90973 91177308-0d34-0410-b5e6-96231b3b80d8
stores is not phi translating, thus it miscompiles really
crazy testcases. This is from inspection, I haven't seen
this in the wild.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@90930 91177308-0d34-0410-b5e6-96231b3b80d8
phi translation of complex expressions like &A[i+1]. This has the
following benefits:
1. The phi translation logic is all contained in its own class with
a strong interface and verification that it is self consistent.
2. The logic is more correct than before. Previously, if intermediate
expressions got PHI translated, we'd miss the update and scan for
the wrong pointers in predecessor blocks. @phi_trans2 is a testcase
for this.
3. We have a lot less code in memdep.
We can handle phi translation across blocks of things like @phi_trans3,
which is pretty insane :).
This patch should fix the miscompiles of 255.vortex, and I tested it
with a bootstrap of llvm-gcc, llvm-test and dejagnu of course.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@90926 91177308-0d34-0410-b5e6-96231b3b80d8
that I'm working on. This is manifesting as a miscompile of 255.vortex
on some targets. No check lines yet because it fails.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@90520 91177308-0d34-0410-b5e6-96231b3b80d8
handle cases like this:
void test(int N, double* G) {
long j;
for (j = 1; j < N - 1; j++)
G[j+1] = G[j] + G[j+1];
}
where G[1] isn't live into the loop.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@90041 91177308-0d34-0410-b5e6-96231b3b80d8
translation of add with immediate. This allows us
to optimize this function:
void test(int N, double* G) {
long j;
G[1] = 1;
for (j = 1; j < N - 1; j++)
G[j+1] = G[j] + G[j+1];
}
to only do one load every iteration of the loop.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@90013 91177308-0d34-0410-b5e6-96231b3b80d8
where it is not available. It's unclear how to get this inserted
computation into GVN's scalar availability sets, Owen, help? :)
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@89997 91177308-0d34-0410-b5e6-96231b3b80d8
if it is not ultimately captured. Teach BasicAliasAnalysis that a
local object address which does not escape and is never stored does
not alias with a value resulting from a load.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@89398 91177308-0d34-0410-b5e6-96231b3b80d8
from GVN, this also speeds it up, inserts fewer PHI nodes (see the
testcase) and allows it to remove more loads (due to fewer PHI nodes
standing in the way).
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@83746 91177308-0d34-0410-b5e6-96231b3b80d8
This doesn't kick in too much because of phi translation issues,
but this can be resolved in the future.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@82447 91177308-0d34-0410-b5e6-96231b3b80d8
from a piece of a large store when both are in the same block.
This allows clang to compile the testcase in PR4216 to this code:
_test_bitfield:
movl 4(%esp), %eax
movl %eax, %ecx
andl $-65536, %ecx
orl $32962, %eax
andl $40186, %eax
orl %ecx, %eax
ret
This is not ideal, but is a whole lot better than the code produced
by llvm-gcc:
_test_bitfield:
movw $-32574, %ax
orw 4(%esp), %ax
andw $-25350, %ax
movw %ax, 4(%esp)
movw 7(%esp), %cx
shlw $8, %cx
movzbl 6(%esp), %edx
orw %cx, %dx
movzwl %dx, %ecx
shll $16, %ecx
movzwl %ax, %eax
orl %ecx, %eax
ret
and dramatically better than that produced by gcc 4.2:
_test_bitfield:
pushl %ebx
call L3
"L00000000001$pb":
L3:
popl %ebx
movl 8(%esp), %eax
leal 0(,%eax,4), %edx
sarb $7, %dl
movl %eax, %ecx
andl $7168, %ecx
andl $-7201, %ebx
movzbl %dl, %edx
andl $1, %edx
sall $5, %edx
orl %ecx, %ebx
orl %edx, %ebx
andl $24, %eax
andl $-58336, %ebx
orl %eax, %ebx
orl $32962, %ebx
movl %ebx, %eax
popl %ebx
ret
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@82439 91177308-0d34-0410-b5e6-96231b3b80d8
early for the stated reasons: this allows it to find more
equivalences and depend less on code layout.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@82404 91177308-0d34-0410-b5e6-96231b3b80d8
so that nonlocal and partially redundant loads can use it as well.
The testcase shows examples of craziness this can handle. This triggers
*many* times in 176.gcc.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@82403 91177308-0d34-0410-b5e6-96231b3b80d8
(and load -> load) when the base pointers must alias but when
they are different types. This occurs very very frequently in
176.gcc and other code that uses bitfields a lot.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@82399 91177308-0d34-0410-b5e6-96231b3b80d8
input filename so that opt doesn't print the input filename in the
output so that grep lines in the tests don't unintentionally match
strings in the input filename.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@81537 91177308-0d34-0410-b5e6-96231b3b80d8
- I'd appreciate it if someone else eyeballs my changes to make sure I captured
the intent of the test.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@81083 91177308-0d34-0410-b5e6-96231b3b80d8
instead of a bool argument, and to do the dominator check itself.
This makes it eaiser to use when DominatorTree information is
available.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@80920 91177308-0d34-0410-b5e6-96231b3b80d8
so that all code paths get it. PR4256 was about a case where the
phi translation loop would find all preds in the Visited cache, so
it could get by without re-sorting the NonLocalPointerDeps cache.
Fix this by resorting it earlier, there is no reason not to do this.
This patch inspired by Jakub Staszak's patch.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@75476 91177308-0d34-0410-b5e6-96231b3b80d8
move loads back past a check that the load address
is valid, see new testcase. The test that went
in with 72661 has exactly this case, except that
the conditional it's moving past is checking
something else; I've settled for changing that
test to reference a global, not a pointer. It
may be possible to scan all the tests you pass and
make sure none of them are checking any component
of the address, but it's not trivial and I'm not
trying to do that here.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@73632 91177308-0d34-0410-b5e6-96231b3b80d8
low-level alias() method, allowing it to reason more aggressively
about pointers into constant memory. PR4189
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@72403 91177308-0d34-0410-b5e6-96231b3b80d8
analyses could be run without the caches properly sorted. This
can fix all sorts of weirdness. Many thanks to Bill for coming
up with the 'issorted' verification idea.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@62757 91177308-0d34-0410-b5e6-96231b3b80d8
visited set before they are used. If used, their blocks need to be
added to the visited set so that subsequent queries don't use conflicting
pointer values in the cache result blocks.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@61080 91177308-0d34-0410-b5e6-96231b3b80d8
cleans up the generated code a bit. This should have the added benefit of
not randomly renaming functions/globals like my previous patch did. :)
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@61023 91177308-0d34-0410-b5e6-96231b3b80d8
memdep keeps track of how PHIs affect the pointer in dep queries, which
allows it to eliminate the load in cases like rle-phi-translate.ll, which
basically end up being:
BB1:
X = load P
br BB3
BB2:
Y = load Q
br BB3
BB3:
R = phi [P] [Q]
load R
turning "load R" into a phi of X/Y. In addition to additional exposed
opportunities, this makes memdep safe in many cases that it wasn't before
(which is required for load PRE) and also makes it substantially more
efficient. For example, consider:
bb1: // has many predecessors.
P = some_operator()
load P
In this example, previously memdep would scan all the predecessors of BB1
to see if they had something that would mustalias P. In some cases (e.g.
test/Transforms/GVN/rle-must-alias.ll) it would actually find them and end
up eliminating something. In many other cases though, it would scan and not
find anything useful. MemDep now stops at a block if the pointer is defined
in that block and cannot be phi translated to predecessors. This causes it
to miss the (rare) cases like rle-must-alias.ll, but makes it faster by not
scanning tons of stuff that is unlikely to be useful. For example, this
speeds up GVN as a whole from 3.928s to 2.448s (60%)!. IMO, scalar GVN
should be enhanced to simplify the rle-must-alias pointer base anyway, which
would allow the loads to be eliminated.
In the future, this should be enhanced to phi translate through geps and
bitcasts as well (as indicated by FIXMEs) making memdep even more powerful.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@61022 91177308-0d34-0410-b5e6-96231b3b80d8
